Transmission or front differential problems

[ttzcar]

2002 4.4i idk the mileage, pixels have been out for 3 years now.
Yesterday I was on the freeway and out of nowhere the RPMs just flew up and the X was not going. I've had no known transmission problems or symptoms prior to this.
I'll try and make this short and sweet, because there's more to this story.
I had to get the car towed. My pixels are out, so I have no idea what my car is telling me. I just hear beeps.

When I got home, I was able to go through all the gears in sport mode. But no matter what gear I'm in, even reverse it does not move. Also, the X5 doesn't hold Park. If I put it in Park it will still roll. Also...

I got underneath the car and there is fluid leaking. It appears it's from the front differential, passenger side. ALSO!!! the passenger side front axle is about 2 inches separated from the differential. Hence where the oil is leaking from. Here's the story on that... I remember when I installed that axle, the lock-ring was really squished and flat up against it and it wouldn't really lock at all. It would pull out with the slightest of tugs. So... I'm assuming it came out? Here's the thing, even if it comes out slightly, the splines should still grab correct? Maybe that 2 inch gap, it came way out? If in fact that axle stripped or just came out, would it make sense that that is the reason my car is not moving? The drive-train power is exiting there? Also why it won't hold park? When my drive-shaft stripped, it was doing the same thing?

This seems right? I'm just crossing my fingers that it's not my tranny. But as I mentioned my tranny will shift through all the gears and it never went into limp mode and I was normally cruising on the highway at 75 mph.

Any info please.